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January 22

 

Home Impact ! Photos Essay Thank You! Links

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magnificent 9" x 14" full-size view!

 

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Living stromatolites (formed by colonies of cyanobacteria) at Chetumal, Mexico.  Note the grass growing on the top of some.

Stromatolites are thought to be the first living organisms on this planet.  3.8 billion years ago, the Earth was a very different place.  There was no ozone layer, the atmosphere was primarily carbon dioxide, and dry land was constantly sterilized by deadly UV-C rays from the Sun.  Bacteria ruled world, but they made a mistake...  they filled the entire ocean and the entire atmosphere with a corrosive, reactive, poisonous gas and paved the way for higher life-forms to assume control of the Earth.  That gas is oxygen.  It filters harmful solar rays, and its vigorous chemical reactivity allows organisms to maintain a very high, and therefore efficient, metabolic rate.

Cyanobacteria give off O2 as waste.  It's poisonous to them.  Today, we're filling the atmosphere with poisonous wastes of our own just as they did.  If germs can pollute the entire planet so might we,   Apparently, we're no smarter than bacteria.

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Originally, I thought this lens of mud underlain by a bed of clasts was a cut-off meander from an ancient stream.  To the contrary, Kevin explained that it was more likely a small cave-like structure with some collapse breccia at its bottom surface which was later filled in with modern soil.  But of course!  All the signs are there.  I have much to learn.
jpegktexpedition0122011115.jpg (162161 bytes) We found a new outcrop of the K/T boundary in this quarry.  It's the closest yet to ground zero.
jpegktexpedition0122011238.jpg (345703 bytes) More scouting for the boundary.  Dan (the film crew sound man) and Adriana are shown here on a very steep slope of the Rio Hondo in Mexico.

 

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This page was last updated on 07/22/01

To make a comment, ask questions, report problems, etc., please contact

Reuben Johnson at: rcjohnson@students.wisc.edu